XInitThreads

XInitThreads is a function in the X Window System that allows a multithreaded application to initialize threading support for its Xlib client. Xlib, the C language interface to the X Window System, is not inherently thread-safe. Calling XInitThreads() before any other Xlib calls enables the use of Xlib in a multithreaded environment. Without this initialization, using Xlib functions from multiple threads can lead to unpredictable behavior, crashes, and data corruption.

The function typically takes no arguments and returns a success or failure indicator. Once XInitThreads() has been successfully called, applications can safely make Xlib calls from different threads. This is crucial for modern graphical applications that employ threading for responsiveness, such as performing network operations or heavy computations in background threads while keeping the user interface responsive. It is important to note that XInitThreads() should be called only once per application. Repeated calls or calling it after other Xlib functions have been invoked will result in an error. The thread that calls XInitThreads() becomes the "main" Xlib thread, and other threads that wish to interact with the X server must also be properly managed in conjunction with this initialization.